The present invention relates to reversibly metachromatic printed matter prone to change in color in response to temperature change. The printed matter of the invention will be used preferably as transfer paper sheets or as decorative seals.
There are known in the art some kinds of printed matter prepared using (a) metachromatic ink(s) such that characters and/or figures will appear on them at prescribed temperatures (see for example the Japanese Utility Model Publications No. Hei.4-6938 and No. Hei.4-6939).
Each of such printed matter comprises an underlayer of a non-metachromatic ink (viz., an ordinary ink) applied to a substrate so as to provide any desired characters and/or figures. An upper layer covering the non-metachromatic under-layer is composed of a thermally metachromatic ink so that any superimposed image will lose or restore its color in response to change in temperature. The whole surface area of such a non-metachromatic printed image is completely covered with the metachromatic image in the prior art printed matter.
At room temperature or moderate temperatures, the colored meta-chromatic print hides the non-metachromatic print, whereby such a prior art printed matter sheet will be observed as if it were an entirely monochromatic sheet. However at predetermined temperatures, the metachromatic printed image in the upper layer of the printed matter will become colorless, thus rendering visible the underlying non-metachromatic printed image such as characters.
As discussed above, those prior art printed matter sheets have been printed with such a thermally metachromatic ink covering the entirety of non-metachromatic printed image. Therefore, characters and the like have been allowed to appear in a normal solid-color surface, in a simple manner failing to afford any peculiar or ornamental effect.
An object of the present invention is to provide a novel type of printed matter that can produce a more fantastic visual effect in use.
Each surface of the printed matter of the invention is composed of a first image printed with at least one of first thermo-metachromatic colorants prone to reversible change in color due to change in ambient temperature, and a second image printed either with a non-metachromatic colorant or with at least one of second thermo-metachromatic colorants prone to change in color at temperatures different from those at which the first colorants will change their color. The first and second images proposed herein may be printed on respective discrete regions in the printed matter surface.
In this invention, the concept of xe2x80x98reversible change in color in response to ambient temperaturexe2x80x99 as summarized above does include color change between chromatic colors such as red and yellow, color change between a chromatic color and an achromatic color for example between red and white, and color change between any chromatic or achromatic color and transparency for example between red and transparency.
The term xe2x80x98printed imagesxe2x80x99 used herein include characters, letters, figures and the like.
As mentioned above, the thermally metachromatic image and the thermally non-metachromatic image may be printed on the discrete regions in the printed matter of the invention. This means that the latter image will be sensed irrespective of any change in temperature so as to provide a basic pattern to which the former metachromatic image is added at prescribed temperatures.
In another mode of carrying out the present invention, either the first or second printed image may occupy an almost entire region of the printed matter surface, and correspondingly either the second or first image occupies at least one portion of the remainder region so as to serve as a background image or scene.
Thus, either of the printed images is disposed fully over the entire surface, to be accompanied by the background that is formed with the other printed image capable of producing various scenes such as a summer scene, a winter scene or any other designed scene.
In still another mode, the first and second printed images may be line drawings that are of the same configuration at least in part and overlap one another at least in part.
Such a composite image consisting of the line drawings overlapping one another at least partially will not greatly change its pattern but will merely change its color.
In a further mode, the first printed image may be superimposed on the second non-metachromatic image so as to expose a part thereof.
This type of the printed matter comprises the metachromatic image formed with a metachromatic colorant reversibly changeable between its colorless state and its colored state.
In contrast with the prior art overlying thermo-metachromatic image completely covering the underlayer, the overlying metachromatic layer in this invention does hide only in part the non-thermo-metachromatic underlayer image. Therefore, a curious impulse will come over any viewer of this printed matter, wondering what is a hidden part of that image underlying the surface layer.
In a still further mode, the first printed image may be superimposed on the second printed image of a meaning relevant to the first one.
Such a non-metachromatic and metachromatic images in the printed matter of the invention are of supplementary meanings to give viewers an intellectual impression or a feeling of curiosity.
The first image may be formed of any thermo-metachromatic colorant that reversibly changes in color depending on ambient temperature, from its colorless state to its colored state or vice versa.
If the second image is formed of at least one of second thermo-metachromatic colorants prone to change in color at temperatures different from those at which the first colorants will change their color, the second thermo-metachromatic colorant may be one that reversibly changes in color depending on ambient temperature, from its colorless state to its colored state or vice versa.
The printed matter summarized above may be used as transfer sheets or as seals, and the first printed image may be a polychromatic image of two or more colors.